The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spectrometer contains nine germanium detectors that are positioned behind the nine grid pairs on the telescope. These artificially grown crystals, pure to over one part in a trillion, were manufactured by the ORTEC division of PerkinElmer Instruments. When they are cooled to cryogenic temperatures and a high voltage is put across them (up to 4000 V), they convert incoming x-rays and gamma-rays to pulses of electric current. The amount of current is proportional to the energy of the photon, and is measured by sensitive electronics designed at the Lawrence Berkeley National Laboratory and the Space Sciences Lab., Berkeley. The detectors are cooled with a recently developed electromechanical cryocooler (built by Sunpower, Inc. and flight qualified at Goddard. It maintains them at the required operating temperature of minus 324 degrees Fahrenheit (minus 198 degrees Centigrade, or 75 degrees above absolute zero). For more information, see: http://hesperia.gsfc.nasa.gov/hessi/instrumentation.htm Group: Instrument_Details Entry_ID: HESSI SPECTROMETER Group: Instrument_Identification Instrument_Category: Solar/Space Observing Instruments Instrument_Class: X-Ray/Gamma Ray Detectors Short_Name: HESSI SPECTROMETER End_Group Group: Associated_Platforms Short_Name: RHESSI End_Group Group: Spectral_Frequency_Information Wavelength_Keyword: X-Ray Number_Channels: 1 End_Group Online_Resource: http://hesperia.gsfc.nasa.gov/hessi/hessispec.htm Sample_Image: http://hesperia.gsfc.nasa.gov/hessi/images/detectors.jpg Group: Instrument_Logistics Instrument_Start_Date: 2002-02-05 Instrument_Owner: NASA/GSFC End_Group End_Group
HESSI SPECTROMETER
X-Ray/Gamma Ray Detectors